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Thanks for the help, all of a sudden, it started working again, so I think something else was going on.
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Thanks for the help, all of a sudden, it started working again, so I think something else was going on.

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Hello Experts,<br />
<br />
As part of the steps to migrate onto Office 365, I added our external domain name as an alternative UPN suffix within Active Directory and after doing so, we are no longer able to access our company websites internally.<br />
<br />
I suspect that adding the UPN suffix has created an DNS issue internally and I am unclear how to resolve it, any information would be greatly appreciated.<br />
<br />
Below is our network configuration; <br />
<br />
Internal Domain<br />
cadcasbs.local<br />
<br />
External Domain<br />
cadca.org<br />
<br />
External Websites trying to access internally<br />
<a href="http://www.cadca.org" rel="ugc">www.cadca.org</a><br />
drugfreekids.cadca.org<br />
forum.cadca.org<br />
<a href="https://filedb.experts-exchange.com/incoming/2013/10_w43/684509/cadcadnsconfiguration.PNG" target="_blank" class="file-inline" title="DNS configuration (65 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>cadcadnsconfiguration.PNG</a>
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cadcadnsconfiguration.PNG

Hello Experts,

As part of the steps to migrate onto Office 365, I added our external domain name as an alternative UPN suffix within Active Directory and after doing so, we are no longer able to access our company websites internally.

I suspect that adding the UPN suffix has created an DNS issue internally and I am unclear how to resolve it, any information would be greatly appreciated.

Below is our network configuration; 

Internal Domain
cadcasbs.local

External Domain
cadca.org

External Websites trying to access internally
www.cadca.org
drugfreekids.cadca.org
forum.cadca.org

Unable to access company websites internally after adding an alternative UPN suffix to Active Directory

Office 365 is a group of software plus services subscriptions that provides productivity software and related services to its subscribers. Office 365 allows the use of Microsoft Office apps on Windows and OS X, provides storage space on Microsoft's cloud storage service OneDrive, and grants 60 Skype minutes per month. Office 365 includes e-mail and social networking services through hosted versions of Exchange Server, Skype for Business Server, SharePoint and Office Online, integration with Yammer, as well as access to the Office software. All of Office 365's components can be managed and configured through an online portal; users can be added manually, imported from a CSV file, or Office 365 can be set up for single sign-on with a local Active Directory using Active Directory Federation Services.

Microsoft 365

The Domain Name System (DNS) is a hierarchical, globally distributed system responsible for associating the name of a computer, service or other resource into an IP address for connecting to the Internet or a private network. Most prominently, it translates domain names to the numerical IP addresses needed for the purpose of computer services and devices worldwide.